I initially had the same complaints about moving to Swift, especially with regards to dynamically created objects.

However I have found benefit in having strict model types that my JSON data must map into — or else cause compiler errors. I far prefer to pick up problems up at compile time then learn about them at run time.

Yup, ObjC is light and scripty. Whenever you don't like what it's doing you just make it do what you want, categories, cast to id, swizzling, respondsTo, NSSelectorFromString, etc, and when it's too slow you write those functions in C/C++ which it integrates well with.

Swift you're always contorting yourself to express things in a way that the language wants, it reminds me of writing java, it worships far to heavily at the altar of type safety as if type safety was a goal in and of itself.

Agreed. When I first started out I never could have guessed it would become my favorite language. Apple did a lot of great things during my tenure writing ObjC - GCD and ARC are probably the best. I couldn't believe how easy it was to write performant code, both for powerful desktops and power-starved mobile devices.

It was the first place (pre-ARC) that I learned to manage my own memory, and the first (pre-GCD) that I learned to be as safe as possible in a multi-threaded environment.

If in fact Swift is the death-knell of Objective-C, I will be sad. I've written C and C++ and Python and Go and Scheme and Lisp and on and on (Java, C#...) and it will remain one of my favorites for years to come.

By academic, I meant academic problems that Swift solves such as increased type safety...

Not academic research as in we did a study of developers who write iOS apps and determined that type safety as implemented in swift helps great developers write apps faster. (F# on the other than has a great type system that doesn't get in your way)

Choosing more type safety over less is a pragmatic concern - one input among many into the cost benefit analysis we all do when picking languages and platforms. More type-safe languages tend to have more boilerplate and hoops to jump through, but they also tend to be more robust. The latter can be proven theoretically more efficiently than with empirical research, but it is no less true for it. We are limited by the laws of mathematics, however 'pragmatic' we fancy ourselves.

Having never written a line of swift or ObjC, I have no opinion on the matter at hand. I also make my money out of the thoroughly unsafe Javascript. But it's not a good idea to blithely dismiss type safety as an ivory tower concern of academic CS. The benefits are real, and can be measured in the number of panicked pages/emails received at 3am.

None taken, many great projects such as the Linux kernel are written in languages with near zero type safety, and their authors with tremendous experience continue to this day to advocate the choice of languages with poor type safety over those with excellent type safety.

I think it's worth hearing Linus out on the reasons you might want to choose a less type safe language over a type safe one.

OK, there's a difference here between “type correctness” (your binary NOT trying to apply a string function to a floating-point number, e.g.) and “type safety” (your language using formal methods to ensure type correctness). If you as the programmer are willing and able to ensure type correctness manually, the type safety of your language becomes close to irrelevant. It's just that not everyone is a kernel programmer who needs the extra oomph you get if you sacrifice type safety.

It can be used in ways that provide more type safety than C. (And people do - that's part of why not every C++ program is a crumbling ruin.) But people (including Linus) choose not to use that extra safety. They have their reasons, not all of which are stupid.

If you use swift features then your class is inaccessible to ObjC. If you mark your class @objc then you can't use many swift features.

The only thing that works well is writing most of your app in swift and writing ObjC wrappers for C/C++ code, because dealing with C in Swift is atrocious and many libraries simply don't work in Swift because of initialization issues with complex structs.

Also, having two tools to choose from that do practically the same thing is never really a good idea because you waste time trying to figure out whether Swift->ObjC interop is going to fuck you over more than ObjC->Swift interop for this particular class.

Also, once you start mixing code and have your code importing a Swift header and your Swift bridging header importing your ObjC classes you start getting huge compile times as anytime you change an ObjC header your entire swift code has to be recompiled which takes forever because the swift compiler is dog slow.

My advice, pick one language for your project and stick with it, the language I would advise until Apple writes base libraries in Swift is ObjC, because if you run into performance issues C/C++ is going to save your ass far more than Swift will.

For anyone who isn't familiar, Aaron is one of the most venerable Objective-C programmers out there. He worked at NeXT in the '90s and has been teaching new Objective-C programmers since OS X was released.

Can I blissfully go on writing OS X and iOS apps in Objective-C (I spent 15+ years training brain cells in Obj-C)? Aaron H. seems to suggest I can -- Apple isn't just pong to deprecate the entire language one morning in early June I hope. I have learned just enough Swift to read it, but not ready to invest the time to learn it well.

You're definitely safe writing your own apps in it for well into the foreseeable future — there's not only way too much app code out there for it to be deprecated soon, but the vast majority of the system and bundled apps are in Objective-C.

I'd expect Objective-C jobs, though, to decline in number over time as Swift jobs rise. If you're doing it professionally, not learning Swift is going to increasingly limit your options, perhaps pretty rapidly — a few months ago, I got turned down for a job in part because of lack of Swift experience. Ended up landing a different job where we're writing a Swift app and step 1 for everyone on the team was "learn Swift".

ObjC is far from dead for me. And it will take Swift a long time (if ever) to deliver what ObjC can do.

Swift is not completely bad per se, but it's far from being as approachable as C. In C, you only need to read all the header files, then you “know everything”. In Swift, there aren't even any files with declarations you _could_ read. But then, a completely obscure language seems like a perfect fit for a walled garden.

The text below was simply excerpts instead of the full transcript. The incomplete excerpts looked like snippets of context to guide people to the middle parts of the video. You actually had to watch/listen to the video to get the full text.

For example, at the beginning, he says the word "tricycle" and when I searched for that word, it wasn't in the text below. That's when I knew it wasn't a full transcript.

True. We edit the transcript on purpose to make it more useful to people who want to read it instead of watching the video. If you're looking for a full word-for-word transcript, we have that through the subtitles available in the video. We iterated towards this model after a lot of trial & error but we're still looking for feedback on what people would prefer to see!

The developments that Facebook is working on with React Native are just so much more exciting than another riff on C++. For most "utility" apps, I just don't think performance is such an issue that the point of research should be these (comparably) incredibly low level concerns.

When I see the bugs going on in iOS apps, it has to do with models that are broken for what modern programs looks like today: things like asynchronicity. Animation is still a mess to wrap your mind around when you have a series of asynchronous events (animations, loads, what have you) that are tied together, but can also be canceled half way through. This is why I can still break many apps by just tapping all over the place (or clicking all over the place: http://tolmasky.com/letmeshowyou/Yosemite/Safari%20Animation... ).

Now, of course the elephant in the room is that neither of these matter that much when most the apps being written are games that will continue using C++ or Unity (if you actually care about speed these are your best bet). Especially with the work Apple is doing with Metal that will improve these platforms as well.

Yeah... I'm pretty certain the only code in iOS 9 that is written in Swift is the Calculator app, which was also the first app I remember Apple shipping that actually used their public version of UIKit; until iOS 4, when Apple dogfooding their library finally made UIKit "good", Apple was still using the as-yet-much-better private UIKit they had written for iOS 1 that shared very little... it even had its own UIScrollView called UIScroller and its own UITableView called UITable. While I'm sure the language keeps getting better as people provide feedback, the product isn't going to move past that "omg this is amazing" threshold until Apple dogfoods it, and until then Apple is just using everyone as guinea pigs ;P.

FWIW, I think Apple can't ship any base libraries that uses Swift until they finish ABI-compatibility, as they need to be working off the same base Swift runtime as the apps that would run against those libraries. Given that for the last year people have been shipping apps that link against an old-and-incompatible Swift runtime that Xcode bundles into your app, and given how the runtime is "intrusive" (putting stuff into the global Objective-C namespace, for example), it isn't even clear yet (so this may require more time on their end to build out more infrastructure) how they will be able to pull that off without saying "all Swift apps developed before now need to be reshipped or they will stop working on iOS 10".

You hit the nail on the head here. Until the ABI is finalized, Apple can't ship dynamic libraries to developers that are written in Swift. Swift won't be ready to fully replace Obj-C until this happens.

Exactly. I'm not being judgemental about that, but I don't see myself wanting to invest time into being a guinea pig. If Apple wants to build a tool that only works in and for their walled garden, I won't donate any work to it.

Objective C has been around since the 1980s, it has a long history with NeXT and Apple thus is very mature. Code you write in Objective C now can reasonably be expected to stay very similar going forward. Swift however is still very much in the wind where you run into "well this language feature has not been implemented yet" and with each version that is released your code needs to be migrated or changed to accommodate the changes in the language. The path forward is clear with Objective C vs Swift where you just don't know if some of the issues will even be addressed. I've been writing Objective C since 2007 and Swift since shortly after it was released. Swift still has a long way to go before I would use it as the starting language for a new app that I expected to have users / maintain.

I'm not sure, I've had great fun learning it, and writing it is usually really nice. Sure, there have been pains along the way, but the Apple engineers are doing an amazing job with evolving Swift, intelligently, and very quickly. It is the future, and for many developers I know, it is already part of the present.

Hearing one of the core engineers from the LLVM compiler team speak at some length about their aims and approach to Swift, it was cleat that they had reflected long and hard on the approaches of many other languages. This engineer had very informed and nuanced views on the strengths and weaknesses of pretty much any other language you asked about. I'm sure Scala was on this list, also "Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and far too many others to list" — http://www.nondot.org/sabre/

I've been working on a medium-sized Swift 1.2 app for the last few months and, while it's come a long way from 1.0, I still don't think I'd recommend it for new work yet. Compile times are agonizingly long, even worse than C++.

If I didn't have so much code in objective-c - I'd welcome the passing. Until then - I've built a project to migrate objective-c code > swift en masse.
check out http://objc2swift.io for hockeyapp download.

As IOKit is a child of DriverKit which was implemented in ObjC we
wanted to reduce the amount of work necessary to convert from one
space to the other, as ObjC is single inherited this was easiest for
most of our drivers. At first we were going to allow multiple
inheritance as we ported to C++ but then we tripped over the whole
can of worms called 'virtual' inheritance. We really, really didn't
want to turn all of our developers into C++ experts, which you have
to be to use virtual inheritance properly. Another side effect is
that we are now reasonable language independent. At some stage in
the future we may be able to move IOKit over to a good programming
language.

I suspect that if they had re-written IOKit in 2010, it would be in Objective-C. My guesses why it was done in C++ in 2000:

- programmer familiarity/comfort level: remember that classic Mac development was mostly being done in C/C++ by the mid-90s, and the Mac developers still around by 2000 didn't need to be given more reasons to jump ship. Carbon was created so that Mac C/C++ applications could be brought to X, and having drivers written in C++ was another easing factor.

This also includes Apple's internal development teams--I don't think all the longtime Apple teams were that bullish on NeXT technologies. Remember that the original OS X Finder was a C++ Carbon app built with CodeWarrior.

- ObjC not considered inevitable: in 2000 it was not at all clear that ObjC would be thriving for another 15+ years. The C/C++ Carbon API was one direction for the future, the Cocoa-Java bridge was another, another was putting C++-style syntax on top of ObjC (which was never completed). C++ wasn't going anywhere, whereas it would be painful to have driver development handcuffed to ObjC if applications abandoned it.

- performance: it probably would have been a non-issue, but C++ is a safer choice performance-wise.

There might be other interesting tidbits on the darwin-development or darwin-drivers if you go back to 2000/2001.

In Obj-C for example, there are no "methods" like C++, in C++ when you put a method in a class, (although implementation details may vary) it works like a function pointer in a C struct, and calling that method is just executing whatever code that pointer points to.

In Obj-C in contrast, to call a function of a class, you actually pass a message, that first must be interpreted, then the runtime that interpreted the message find the correct function definition to use and run.

For most apps people don't care about this, but game developers for example frequently make iOS and Mac games that in time-critical parts use pure C or even Obj-C++ so that they can skip this messaging part (that can cause significant performance problems sometimes).

Example: yesterday I was trying to figure why a open source game I like was slowing down, I ran a profiler, and the most called function, and the one with most execution time, was a simple "GetSomeRandomVar()" for spaceships (it is a spacefight battle game), I looked in the source, and saw that every frame, every spaceship call this at least once for every other spaceship, if the spaceship has an AI it calls it many, many times, I inlined it and the code became much faster.

I am very sure that if it was a ObjC call (with messaging) it would be so slow that the original author probably would not even have uploaded that to github. (by the way, the game IS an OSX game, but the original author wisely decided to go with C++ instead of ObjC)

I think putting it that way exaggerates the differences a bit. The message doesn't really have to be "interpreted" in any meaningful way AFAIK. A message consists of a selector (essentially a method name) and a receiver, then whatever other arguments the method will take. The runtime looks up the selector in the receiver's method table, much like with C++ virtual methods, and then jumps to the implementation it finds. There is a little more fanciness (some method caching, and support for nil receivers), but I don't feel like it's hugely dissimilar from virtual methods.

The vtable is a flat structure with known layout in C++. In Objective-C, it's a hash table (with precomputed hashes and lots of other tricks—but it's still fundamentally a hash table). There's a big difference between the two.

There's a big difference between the data structures, yes, but the basic logic for message sends is still pretty similar. They both boil down to a simple lookup in a data structure and a jump. Would you really characterize the difference between a vtable and a hash table as "you actually pass a message, that first must be interpreted" in the case of a hash table?